Ion implantation is a standard technique for introducing conductivity-altering impurities into a workpiece. A desired impurity material is ionized in an ion source, the ions are accelerated to form an ion beam of prescribed energy, and the ion beam is directed at the surface of the workpiece. The energetic ions in the beam penetrate into the bulk of the workpiece material and are embedded into the crystalline lattice of the workpiece material to form a region of desired conductivity.
LEDs are built on a substrate and are doped with impurities to create a p-n junction. A current flows from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Electrons and holes flow into the p-n junction from electrodes with different voltages. If an electron meets a hole, it falls into a lower energy level and releases energy in the form of a photon. The wavelength of the light emitted by the LED and the color of the light may depend on the band gap energy of the materials forming the p-n junction.
The LED mesa is isolated or passivated in some instances. This may involve a coating to prevent current leakage or shorting on the sidewall of the mesa. Some methods involve a photolithographic patterning step prior to adding a dielectric thin film, but such methods involve extra process steps, complexity, and cost. Accordingly, there is a need in the art for improved methods of isolation in LEDs.